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linux/drivers/rtc/rtc-mxc.c
Wolfram Sang 5f54c8a00a rtc: mxc: Initialize drvdata before registering device 
Commit f44f7f96a2 ("RTC: Initialize kernel state from RTC") uncovered
an issue in a number of RTC drivers, where the drivers call
rtc_device_register before initializing the device or platform drvdata.

This frequently results in null pointer dereferences when the
rtc_device_register immediately makes use of the rtc device, calling
rtc_read_alarm.

The solution is to ensure the drvdata is initialized prior to registering
the rtc device.

CC: Alessandro Zummo <a.zummo@towertech.it>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: rtc-linux@googlegroups.com
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
[fixed up commit log -jstultz]
Signed-off-by: John Stultz <john.stultz@linaro.org>
2011-05-06 17:40:10 -07:00

493 lines
12 KiB
C
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/*
* Copyright 2004-2008 Freescale Semiconductor, Inc. All Rights Reserved.
*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*/
#include <linux/io.h>
#include <linux/rtc.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <mach/hardware.h>
#define RTC_INPUT_CLK_32768HZ (0x00 << 5)
#define RTC_INPUT_CLK_32000HZ (0x01 << 5)
#define RTC_INPUT_CLK_38400HZ (0x02 << 5)
#define RTC_SW_BIT (1 << 0)
#define RTC_ALM_BIT (1 << 2)
#define RTC_1HZ_BIT (1 << 4)
#define RTC_2HZ_BIT (1 << 7)
#define RTC_SAM0_BIT (1 << 8)
#define RTC_SAM1_BIT (1 << 9)
#define RTC_SAM2_BIT (1 << 10)
#define RTC_SAM3_BIT (1 << 11)
#define RTC_SAM4_BIT (1 << 12)
#define RTC_SAM5_BIT (1 << 13)
#define RTC_SAM6_BIT (1 << 14)
#define RTC_SAM7_BIT (1 << 15)
#define PIT_ALL_ON (RTC_2HZ_BIT | RTC_SAM0_BIT | RTC_SAM1_BIT | \
RTC_SAM2_BIT | RTC_SAM3_BIT | RTC_SAM4_BIT | \
RTC_SAM5_BIT | RTC_SAM6_BIT | RTC_SAM7_BIT)
#define RTC_ENABLE_BIT (1 << 7)
#define MAX_PIE_NUM 9
#define MAX_PIE_FREQ 512
static const u32 PIE_BIT_DEF[MAX_PIE_NUM][2] = {
{ 2, RTC_2HZ_BIT },
{ 4, RTC_SAM0_BIT },
{ 8, RTC_SAM1_BIT },
{ 16, RTC_SAM2_BIT },
{ 32, RTC_SAM3_BIT },
{ 64, RTC_SAM4_BIT },
{ 128, RTC_SAM5_BIT },
{ 256, RTC_SAM6_BIT },
{ MAX_PIE_FREQ, RTC_SAM7_BIT },
};
/* Those are the bits from a classic RTC we want to mimic */
#define RTC_IRQF 0x80 /* any of the following 3 is active */
#define RTC_PF 0x40 /* Periodic interrupt */
#define RTC_AF 0x20 /* Alarm interrupt */
#define RTC_UF 0x10 /* Update interrupt for 1Hz RTC */
#define MXC_RTC_TIME 0
#define MXC_RTC_ALARM 1
#define RTC_HOURMIN 0x00 /* 32bit rtc hour/min counter reg */
#define RTC_SECOND 0x04 /* 32bit rtc seconds counter reg */
#define RTC_ALRM_HM 0x08 /* 32bit rtc alarm hour/min reg */
#define RTC_ALRM_SEC 0x0C /* 32bit rtc alarm seconds reg */
#define RTC_RTCCTL 0x10 /* 32bit rtc control reg */
#define RTC_RTCISR 0x14 /* 32bit rtc interrupt status reg */
#define RTC_RTCIENR 0x18 /* 32bit rtc interrupt enable reg */
#define RTC_STPWCH 0x1C /* 32bit rtc stopwatch min reg */
#define RTC_DAYR 0x20 /* 32bit rtc days counter reg */
#define RTC_DAYALARM 0x24 /* 32bit rtc day alarm reg */
#define RTC_TEST1 0x28 /* 32bit rtc test reg 1 */
#define RTC_TEST2 0x2C /* 32bit rtc test reg 2 */
#define RTC_TEST3 0x30 /* 32bit rtc test reg 3 */
struct rtc_plat_data {
struct rtc_device *rtc;
void __iomem *ioaddr;
int irq;
struct clk *clk;
struct rtc_time g_rtc_alarm;
};
/*
* This function is used to obtain the RTC time or the alarm value in
* second.
*/
static u32 get_alarm_or_time(struct device *dev, int time_alarm)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
u32 day = 0, hr = 0, min = 0, sec = 0, hr_min = 0;
switch (time_alarm) {
case MXC_RTC_TIME:
day = readw(ioaddr + RTC_DAYR);
hr_min = readw(ioaddr + RTC_HOURMIN);
sec = readw(ioaddr + RTC_SECOND);
break;
case MXC_RTC_ALARM:
day = readw(ioaddr + RTC_DAYALARM);
hr_min = readw(ioaddr + RTC_ALRM_HM) & 0xffff;
sec = readw(ioaddr + RTC_ALRM_SEC);
break;
}
hr = hr_min >> 8;
min = hr_min & 0xff;
return (((day * 24 + hr) * 60) + min) * 60 + sec;
}
/*
* This function sets the RTC alarm value or the time value.
*/
static void set_alarm_or_time(struct device *dev, int time_alarm, u32 time)
{
u32 day, hr, min, sec, temp;
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
day = time / 86400;
time -= day * 86400;
/* time is within a day now */
hr = time / 3600;
time -= hr * 3600;
/* time is within an hour now */
min = time / 60;
sec = time - min * 60;
temp = (hr << 8) + min;
switch (time_alarm) {
case MXC_RTC_TIME:
writew(day, ioaddr + RTC_DAYR);
writew(sec, ioaddr + RTC_SECOND);
writew(temp, ioaddr + RTC_HOURMIN);
break;
case MXC_RTC_ALARM:
writew(day, ioaddr + RTC_DAYALARM);
writew(sec, ioaddr + RTC_ALRM_SEC);
writew(temp, ioaddr + RTC_ALRM_HM);
break;
}
}
/*
* This function updates the RTC alarm registers and then clears all the
* interrupt status bits.
*/
static int rtc_update_alarm(struct device *dev, struct rtc_time *alrm)
{
struct rtc_time alarm_tm, now_tm;
unsigned long now, time;
int ret;
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
now = get_alarm_or_time(dev, MXC_RTC_TIME);
rtc_time_to_tm(now, &now_tm);
alarm_tm.tm_year = now_tm.tm_year;
alarm_tm.tm_mon = now_tm.tm_mon;
alarm_tm.tm_mday = now_tm.tm_mday;
alarm_tm.tm_hour = alrm->tm_hour;
alarm_tm.tm_min = alrm->tm_min;
alarm_tm.tm_sec = alrm->tm_sec;
rtc_tm_to_time(&now_tm, &now);
rtc_tm_to_time(&alarm_tm, &time);
if (time < now) {
time += 60 * 60 * 24;
rtc_time_to_tm(time, &alarm_tm);
}
ret = rtc_tm_to_time(&alarm_tm, &time);
/* clear all the interrupt status bits */
writew(readw(ioaddr + RTC_RTCISR), ioaddr + RTC_RTCISR);
set_alarm_or_time(dev, MXC_RTC_ALARM, time);
return ret;
}
/* This function is the RTC interrupt service routine. */
static irqreturn_t mxc_rtc_interrupt(int irq, void *dev_id)
{
struct platform_device *pdev = dev_id;
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
u32 status;
u32 events = 0;
spin_lock_irq(&pdata->rtc->irq_lock);
status = readw(ioaddr + RTC_RTCISR) & readw(ioaddr + RTC_RTCIENR);
/* clear interrupt sources */
writew(status, ioaddr + RTC_RTCISR);
/* clear alarm interrupt if it has occurred */
if (status & RTC_ALM_BIT)
status &= ~RTC_ALM_BIT;
/* update irq data & counter */
if (status & RTC_ALM_BIT)
events |= (RTC_AF | RTC_IRQF);
if (status & RTC_1HZ_BIT)
events |= (RTC_UF | RTC_IRQF);
if (status & PIT_ALL_ON)
events |= (RTC_PF | RTC_IRQF);
if ((status & RTC_ALM_BIT) && rtc_valid_tm(&pdata->g_rtc_alarm))
rtc_update_alarm(&pdev->dev, &pdata->g_rtc_alarm);
rtc_update_irq(pdata->rtc, 1, events);
spin_unlock_irq(&pdata->rtc->irq_lock);
return IRQ_HANDLED;
}
/*
* Clear all interrupts and release the IRQ
*/
static void mxc_rtc_release(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
spin_lock_irq(&pdata->rtc->irq_lock);
/* Disable all rtc interrupts */
writew(0, ioaddr + RTC_RTCIENR);
/* Clear all interrupt status */
writew(0xffffffff, ioaddr + RTC_RTCISR);
spin_unlock_irq(&pdata->rtc->irq_lock);
}
static void mxc_rtc_irq_enable(struct device *dev, unsigned int bit,
unsigned int enabled)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
u32 reg;
spin_lock_irq(&pdata->rtc->irq_lock);
reg = readw(ioaddr + RTC_RTCIENR);
if (enabled)
reg |= bit;
else
reg &= ~bit;
writew(reg, ioaddr + RTC_RTCIENR);
spin_unlock_irq(&pdata->rtc->irq_lock);
}
static int mxc_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
mxc_rtc_irq_enable(dev, RTC_ALM_BIT, enabled);
return 0;
}
/*
* This function reads the current RTC time into tm in Gregorian date.
*/
static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
u32 val;
/* Avoid roll-over from reading the different registers */
do {
val = get_alarm_or_time(dev, MXC_RTC_TIME);
} while (val != get_alarm_or_time(dev, MXC_RTC_TIME));
rtc_time_to_tm(val, tm);
return 0;
}
/*
* This function sets the internal RTC time based on tm in Gregorian date.
*/
static int mxc_rtc_set_mmss(struct device *dev, unsigned long time)
{
/* Avoid roll-over from reading the different registers */
do {
set_alarm_or_time(dev, MXC_RTC_TIME, time);
} while (time != get_alarm_or_time(dev, MXC_RTC_TIME));
return 0;
}
/*
* This function reads the current alarm value into the passed in 'alrm'
* argument. It updates the alrm's pending field value based on the whether
* an alarm interrupt occurs or not.
*/
static int mxc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
rtc_time_to_tm(get_alarm_or_time(dev, MXC_RTC_ALARM), &alrm->time);
alrm->pending = ((readw(ioaddr + RTC_RTCISR) & RTC_ALM_BIT)) ? 1 : 0;
return 0;
}
/*
* This function sets the RTC alarm based on passed in alrm.
*/
static int mxc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
int ret;
if (rtc_valid_tm(&alrm->time)) {
if (alrm->time.tm_sec > 59 ||
alrm->time.tm_hour > 23 ||
alrm->time.tm_min > 59)
return -EINVAL;
ret = rtc_update_alarm(dev, &alrm->time);
} else {
ret = rtc_valid_tm(&alrm->time);
if (ret)
return ret;
ret = rtc_update_alarm(dev, &alrm->time);
}
if (ret)
return ret;
memcpy(&pdata->g_rtc_alarm, &alrm->time, sizeof(struct rtc_time));
mxc_rtc_irq_enable(dev, RTC_ALM_BIT, alrm->enabled);
return 0;
}
/* RTC layer */
static struct rtc_class_ops mxc_rtc_ops = {
.release = mxc_rtc_release,
.read_time = mxc_rtc_read_time,
.set_mmss = mxc_rtc_set_mmss,
.read_alarm = mxc_rtc_read_alarm,
.set_alarm = mxc_rtc_set_alarm,
.alarm_irq_enable = mxc_rtc_alarm_irq_enable,
};
static int __init mxc_rtc_probe(struct platform_device *pdev)
{
struct resource *res;
struct rtc_device *rtc;
struct rtc_plat_data *pdata = NULL;
u32 reg;
unsigned long rate;
int ret;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENODEV;
pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return -ENOMEM;
if (!devm_request_mem_region(&pdev->dev, res->start,
resource_size(res), pdev->name))
return -EBUSY;
pdata->ioaddr = devm_ioremap(&pdev->dev, res->start,
resource_size(res));
pdata->clk = clk_get(&pdev->dev, "rtc");
if (IS_ERR(pdata->clk)) {
dev_err(&pdev->dev, "unable to get clock!\n");
ret = PTR_ERR(pdata->clk);
goto exit_free_pdata;
}
clk_enable(pdata->clk);
rate = clk_get_rate(pdata->clk);
if (rate == 32768)
reg = RTC_INPUT_CLK_32768HZ;
else if (rate == 32000)
reg = RTC_INPUT_CLK_32000HZ;
else if (rate == 38400)
reg = RTC_INPUT_CLK_38400HZ;
else {
dev_err(&pdev->dev, "rtc clock is not valid (%lu)\n", rate);
ret = -EINVAL;
goto exit_put_clk;
}
reg |= RTC_ENABLE_BIT;
writew(reg, (pdata->ioaddr + RTC_RTCCTL));
if (((readw(pdata->ioaddr + RTC_RTCCTL)) & RTC_ENABLE_BIT) == 0) {
dev_err(&pdev->dev, "hardware module can't be enabled!\n");
ret = -EIO;
goto exit_put_clk;
}
platform_set_drvdata(pdev, pdata);
/* Configure and enable the RTC */
pdata->irq = platform_get_irq(pdev, 0);
if (pdata->irq >= 0 &&
devm_request_irq(&pdev->dev, pdata->irq, mxc_rtc_interrupt,
IRQF_SHARED, pdev->name, pdev) < 0) {
dev_warn(&pdev->dev, "interrupt not available.\n");
pdata->irq = -1;
}
rtc = rtc_device_register(pdev->name, &pdev->dev, &mxc_rtc_ops,
THIS_MODULE);
if (IS_ERR(rtc)) {
ret = PTR_ERR(rtc);
goto exit_clr_drvdata;
}
pdata->rtc = rtc;
return 0;
exit_clr_drvdata:
platform_set_drvdata(pdev, NULL);
exit_put_clk:
clk_disable(pdata->clk);
clk_put(pdata->clk);
exit_free_pdata:
return ret;
}
static int __exit mxc_rtc_remove(struct platform_device *pdev)
{
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
rtc_device_unregister(pdata->rtc);
clk_disable(pdata->clk);
clk_put(pdata->clk);
platform_set_drvdata(pdev, NULL);
return 0;
}
static struct platform_driver mxc_rtc_driver = {
.driver = {
.name = "mxc_rtc",
.owner = THIS_MODULE,
},
.remove = __exit_p(mxc_rtc_remove),
};
static int __init mxc_rtc_init(void)
{
return platform_driver_probe(&mxc_rtc_driver, mxc_rtc_probe);
}
static void __exit mxc_rtc_exit(void)
{
platform_driver_unregister(&mxc_rtc_driver);
}
module_init(mxc_rtc_init);
module_exit(mxc_rtc_exit);
MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
MODULE_DESCRIPTION("RTC driver for Freescale MXC");
MODULE_LICENSE("GPL");
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